DESCRIPTION: This is a revised continuation application. It proposes a longitudinal study among persons with Senile Dementia of an Alzheimer's type (SDAT), comparing day-care users to non-users. The primary outcome is time to entry into institutional long-term care; secondary outcomes include patterns of use of hospital and other health-care services, change in client behaviors, especially aggression and other negative behaviors, change in client physical disability and cognitive function and change in caregiver health and function. The hypotheses are: 1) among persons with SDAT, use of day care, on average, delays placement in institutional long-term care and is mediated by positive effects on client and caregiver health, especially lower rates of negative client behaviors. The study will use a dynamic expansion of the Andersen-- Newman model, by explicitly including short-term services in the model. The study will enroll a cohort of 450 participants, including 225 non-users of day care and 225 day-care users, with the user group equally divided between users of dementia-specific day care and users of day-care programs serving clients with many different conditions. Participants will be followed for 3 years, with assessment every 6 months. Each evaluation will be structured and will include behavioral assessment and direct performance testing of physical disability and cognitive function.